Rotation release for rock drills



Nov. 14, 1939. M, R LL 2,179,643

ROTATION RELEASE FOR ROCK DRILLS Filed July so, 1938 2 Sheets-Sheet 1 INVE,NTOR V J? A/ATW/EW 0 Bees Nov. 14, 1939. V M OFARRELL 2,179,643

ROTATION RELEASE FOR BECK DRILLS Filed July SO, 1958 2 Sheets-Sheet 2 INYENTOR Mwrfifw O/EAEEELL I BY M ATTORNEY Patented Nov. 14, 1939 UNlTED STATES PATENT OFFICE ROTATION RELEASE FOR ROCK DRILLS Application July 30, 1938, Serial No. 222,094

3 Claims.

This invention relates to rock drills and more particularly to mechanism for imparting stepby-step rotary movement to the drill steel.

During the operation of rock drills, particularly those of the stoper type, it is highly desirable at times to disable the rotation mechanism, for example when starting a hole or when the drill steel becomes stuck because of variations in the ground formation. It is accordingly an object of the invention to enable the operator to render the rotation mechanism operative or inoperative at will.

More specific objects are compactness of design; convenience of adjustment; positive locking in rotative position and positive unlocking in n0n-r0tative position; and minimum number of parts required for the conversion from a drill of conventional type.

Other objects and features of the invention will appear more clearly from the following description taken in connection with the accompanying drawings and appended claims.

In the accompanying drawings, which illustrate a preferred embodiment of the invention:

Fig. 1 is a longitudinal section of a fragmentary portion of a rock drill embodying the invention, the section being indicated by the arrows l in Fig. 4, the parts being so adjusted that the rotation mechanism is operative;

Fig. 2 is a longitudinal section similar to Fig. 1, but showing the parts in a different position wherein the rotation mechanism is released;

Fig. 3 is a fragmentary longitudinal section as indicated by the arrows 3 in Fig. 4, showing the passages conveying pressure fluid from the throttle valve to the distributing valve;

Fig. 4 is an end view of Fig. 1, illustrating the locations of the rotation locking plungers;

Fig. 5 is a cross section as indicated by the arrows 5 in Fig. 2; and

Fig. 6 is a cross section as indicated by the arrows 6 in Fig. 2, parts of the rotation mechanism and locking means therefor being broken away.

The terms clockwise and counter-clockwise, wherever they appear in the following description, refer to the direction of rotation as it appears when looking rearwardly, as in the case of Fig. 6.

The illustrative embodiment of the invention comprises the usual arrangement of a cylinder 8, a hammer piston 9 reciprocable therein, a rifle nut Ill secured to the piston, a rifle bar H having spirally arranged splines for cooperation with the rifle nut, a back head l2 secured to the cylinder by means of side bolts 13, a distributing valve chest l4 secured to the cylinder, and a distributing valve l5 in said chest arranged to control the flow of compressed air from a supply groove H3 in the valve chest to ports I! and passages l8 "leading respectively to the rear and to the front ends of the cylinder. The cylinder is provided with the usual exhaust port l9 and passages (not shown) for controlling the movement of the distributing valve l5. It will be understood that if the rifle bar H is unrestrained against rotation, it will oscillate about its axis as the piston reciprocates without imparting any substantial rotary movement to the piston. On the other hand, if the rifle bar is i' held against rotation in one direction only, it will rotate in the other direction during one stroke of the piston and compel the piston to rotate during the opposite stroke (preferably the return stroke) while the rifle bar is restrained from ro-.. tating. Any suitable means may be provided for transmitting the step-by-step rotary movement of the piston to the drill steel (not shown).

Referring particularly to Fig. 6, the rifle bar H has a head 2|] at its rear end which carries pawls 2i adapted to engage an internally toothed ratchet ring 22. The ratchet ring is surrounded by a fixed ring 23 which is held against rotary movement by a key 24, as shown in Fig. 3. Means, including side rods l3, clamp the fixed ring 23 between a valve cap 25 and a disc 26 seated in a recess in back head l2, thereby holding the ring 23 against axial movement. Head 2!) on the rifle bar is similarly confined between the valve cap and disc. Ratchet ring 22 has a flange 21 seated in a counterbore in fixed ring 23 and abutting the end of valve cap 25, whereby axial movement of the ratchet ring is inhibited. In accordance with the present invention, a releasable locking arrangement is provided for holding the ratchet ring 22 against rotary movement. Accordingly, the rear end of the ratchet ring is provided with ratchet teeth 28 adapted for engagement with complementary ratchet teeth on a locking ring 29 which is mounted for limited axial movement in an annular recess in the disc 2'6. The locking ring has three lugs 29a received within complementary recesses in the stationary disc 26 to prevent the locking ring from rotating. Spring pressed plungers 30,- mounted in bores in the fixed ring 23, tend to move the locking ring 29 out of engagement with the teeth 28 on ratchet ring 22. The springs are adapted to be overpowered by pressure transmitted to the opposite or rear face of the locking v ring through a plurality of pins 3| mounted to reciprocate in bores provided in disc 26. The pins are actuated by locking plungers 32 reciprocable within bores or plunger chambers 33 in the back head 12. In the illustrative embodiment of the invention, there are three locking plungers 32 and three releasing plungers 39, each pair of plungers being in alignment with each other and with the associated lug 29a on locking ring 29. The locking plungers are arranged to be operated in unison by fluid pressure, and accordingly the back head is provided with passages 34 establishing communication between the rear ends of the plunger chambers 33, and with another set of passengers 35 providing communication between the front ends thereof. An exhaust port 36, leading from the front end of one of the plunger chambers 33 to atmosphere, provides a means for venting the front ends of the locking plungers 32.

A- manipulative throttle valve 37 controls the supply of pressure fluid, such as live air, to the distributing valve i5, as well as to the plunger chambers 33 for actuating both the hammer piston 9 and the rotation locking plungers 32. The throttle valve is mounted for turning movement within a valve chest 33 integral with the back head and having an exhaust port 39 and a passage 49 leading to the rear end of one of the plunger chambers 33. The throttle valve has an axial bore 4| receiving live pressure fluid from any suitable source, such as an air hose (not shown), and is provided with a peripheral recess 42 communicating at all times with the bore M by means of a radial port 2-3. It will be apparent that when the throttle valve 37 is adjusted to a position in which the peripheral recess 42 registers with passage 40, live air will be admitted to the rear ends of the plunger chambers 33 to cause the plungers 32 and pins 3! to shift the locking ring 29 against the pressure of the spring pressed releasing plungers 39 from the position shown in Fig. 2 to the position shown in Fig. 1, in which the ratchet ring 22 will be held against rotation in a counter-clockwise direction. When the throttle valve is turned approximately 180 away from the Fig. 1 position, however, which is the position shown in Fig. 2, passage id is cut oii from the live air source and is vented through a valve recess 49 and port 39' to release the air pressure on the locking plungers 32 and permit the spring pressed releasing plungers 39 to move the locking ring 29 out of engagement with the ratchet ring 22.

The passages supplying live air to the groove l 6 in the valve chest I d for operating the hammer piston 9 are shown in Figs. 1 and 3. They comprise a pair of ports 35 leading from the bore 4| of the throttle valve and delivering compressed air through passage 36 to a recess ll in the disc 26. pawls 2i and the ratchet ring 22 to an annular recess 48 in the valve cap 35. A passage 49 connects recess 48 with the supply groove it in the valve chest. When the throttle valve is turned to a position about half-way between those shown in Figs. 1 and 2, the supply of live air from the bore ll to both the annular groove l6 and the plunger chambers 33 is cut off.

Summarizing briefly the above described operation, the operator turns the throttle valve 31 from its off position to the position indicated in Fig. 1. Live air is supplied from bore 4'! in the throttle valve through passages 46, 47, 48,49 and l6, from whence it is distributed by the auto- From this recess the air passes between the matic valve l5 alternately to the opposite ends of the hammer piston 9, causing the latter to reciprocate. At the same time, live air, admitted through ports 43 and 49 to the plunger chambers 33, moves the locking plungers 32 forward, causing the pins 3! to move the locking ring 29 in engagement with the ratchet ring 22. During the forward stroke of the hammer piston, the splined connection between'the rifle bar I! and rifle nut It tends to cause the piston to turn counterclockwise and the rifle bar I! clockwise. As apparent from Fig. 6, the pawls 2| permit the rifle bar to turn clockwise at all times and, due to the relatively larger mass of the piston, the rifle bar I l is rotated clockwise without imparting any substantial rotary movement to the piston during the forward stroke. On the return stroke of the hammer piston, the directions in which the piston and rifle bar tend to rotate are reversed. At this time tbe piston is compelled to rotate clockwise because the tendency of the rifle bar to turn in the opposite direction is opposed by the pawls 2!, which prevent the rifle bar from turning counter-clockwise relative to the ratchet ring 22, and by the locking ring 29 which prevents the ratchet ring from rotating counterclockwise relative to the back head l2 and cylinder 8. Thus the rotation mechanism, when adjusted as shown in Fig. i, imparts a step-by-step rotatry movement to the piston 9 and drill steel' (not shown).

When the operator desires to cause the hammer piston 9 to deliver impacts without rotating the drill steel, he turns the throttle valve 180, to the Fig. 2 position. The throttle valve supplies live air to the distributing valve, as hereinbefore described, but cuts off the supply of air operating the rotation locking plungers 32 and permits the spring pressed releasing plungers 39 to move the locking ring 29 out of engagement with the-J ratchet ring 22. When the parts are in the position shown in Fig. 2, the rifle bar ii is free to oscillate or turn in both directions, rotation in a counter-clockwise direction being accompanied by movement of the ratchet ring 22 alongt with the rifle bar and pawls 2 5. Since the rifle bar is free to oscillate relative to the cylinder 8, it does not impart any appreciable turning movement to the piston and the latter may reciprocate without rotating.

From the above description, it will be apparent that the invention may be practiced by converting a conventional rock drill with the addition of a few elements, that the rotation locking and releasing means is quick and positive in action,- and that the operator may quickly and conveniently start or stop the rotation of the drill steel by merely moving the throttle valve.

What is claimed is:

1. A rock drill comprising a cylinder, a ham-" mer piston reciprocable therein and capable of rotation, a riflebar slidaoly engaging the hammer piston for imparting step-by-step rotation thereto, a ratchet ring having a pawl and ratchet connection with the rifle bar, whereby the rifle" bar is permitted to turn only in one direction relative to the ratchet ring, releasable locking means for holding the ratchet ring against rotation in opposite direction relative to the cylinder, said locking means comprising a locking ring' movable axially into and out of locking engagement with the ratchet ring, a fixed ring surrounding said ratchet ring, a plurality of circumferential spaced recesses in said fixed ring, a

spring pressed releasing plunger mounted in each of said recesses and engaging one end of the locking ring to tend to move it toward releasing position, a plurality of circumferential spaced locking plungers on the opposite end of said looking ring, and fluid pressure means for moving said locking plungers against the locking ring to overcome the releasing plungers.

2. A rock drill according to claim 1 in which each of said locking plungers is disposed in axial alinement with an associated releasing plunger.

3. A rock drill comprising a cylinder, a back head secured thereto, a piston reciprocable in the cylinder and capable of rotation, an adjustable throttle valve adapted to be connected to a source of live pressure fluid, a rifle bar slidably engaging the hammer piston for efiecting stepby-step rotation thereof, a ratchet ring having a pawl and ratchet connection with the rifle bar, whereby the rifle bar is permitted to turn only in one direction relative to the ratchet ring, re-

leasable locking means for holding the ratchet ring against rotation in the opposite direction relative to the cylinder, said locking means comprising a locking ring movable axially into and out of locking engagement with the ratchet ring, yieldable means tending to move the locking ring out of engagement with the ratchet ring, and fluid pressure operated means adapted to overcome said yieldable means for moving the locking ring into locking engagement, said fluid pressure means comprising a plurality of plunger chambers in the back head, a locking plunger mounted in each of said chambers, a set of passages connecting one end of each of said chambers to atmosphere, and a second set of passages connecting the opposite ends of said chambers to said live pressure fluid source, said last-mentioned passages being under control of the throttle valve.

MATTHEW OFARRELL. 

